Internally mounted and actuated packer system

ABSTRACT

A packer system for a wellbore. The system includes a base packing element mounted to an inner surface of a first tubular and an actuator which actuates the base packing element in a radially inward direction. The system further includes a first trigger element disposed at the inner surface of the first tubular and operatively connected with the actuator, and a second trigger element disposed at an outer surface of a second tubular. The second tubular is displaceable in an axial direction with respect to the first tubular, wherein, upon displacing the second tubular at a predetermined position within the first tubular: the second trigger element engages with the first trigger element; and the first trigger element causes the actuator to actuate the base packing element in a radially inward direction, to bridge a space between the first tubular and second tubulars. Also disclosed and described is a related method.

BACKGROUND

In the oilfield arts, it is common to bridge an annular gap or space between two downhole tubulars (or tubulars in a wellbore) via an external packer or a set of external seals. In so doing, an annular volume above the packer or seals is effectively sealed off from an annular volume below, to prevent or inhibit migration of fluids or gases (of any type) between the lower and upper annular volumes. By way of example, the two tubulars may be two nested casings, a casing and a liner or a tubing and a casing.

As such, the external packer or external seals are typically mounted on an external cylindrical surface of the “child” tubular, or the tubular with the smaller diameter. Commonly encountered problems include the risk of damage incurred during transport or deployment/actuation of the packer or seals, and related leaks that may occur after actuation.

SUMMARY

This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

In one aspect, embodiments disclosed herein relate to a packer system for a wellbore which includes a base packing element mounted to an inner surface of a first tubular and an actuator which actuates the base packing element in a radially inward direction from a retracted position to an extended position. The system further includes a first trigger element disposed at the inner surface of the first tubular, wherein the first trigger element is operatively connected with the actuator, and a second trigger element disposed at an outer surface of a second tubular. The second tubular is displaceable in an axial direction within and with respect to the first tubular, wherein, upon displacing the second tubular at a predetermined position within the first tubular: the second trigger element engages with the first trigger element; and the first trigger element causes the actuator to actuate the base packing element in the radially inward direction from the retracted position to the extended position, wherein the base packing element bridges a space between the first tubular and the second tubular.

In one aspect, embodiments herein relate to a method which includes: mounting a base packing element at an inner surface of a first tubular; disposing a first trigger element at the inner surface of the first tubular, the first trigger element being operatively connected with an actuator configured to actuate the base packing element in a radially inward direction from a retracted position to an extended position; and disposing a second trigger element at an outer surface of a second tubular, the second tubular being displaceable in an axial direction within and with respect to the first tubular. The method further includes, while displacing the second tubular at a predetermined position within the first tubular, determining whether the second trigger element is matched to engage with the first trigger element of the first tubular. Additionally the method includes, when the second trigger element is matched to the first trigger element: the second trigger element engages the first trigger element; and the first trigger element causes the actuator to actuate the base packing element in the radially inward direction from the retracted position to the extended position, wherein the base packing element bridges a space between the first tubular and the second tubular.

In one aspect, embodiments disclosed herein relate to a packer system for a wellbore which includes a base packing element mounted at an inner surface of a first tubular and which, when in a retracted position, is disposed to be flush or recessed with respect to the inner surface of the first tubular. The system further includes a mechanical actuator which actuates the base packing element in a radially inward direction from a retracted position to an extended position, and at least one receptacle which is placed at the inner surface of the first tubular and is operatively connected with the mechanical actuator. Additionally, the system includes at least one key element placed at an outer surface of a second tubular and which is physically compatible with the at least one receptacle. The second tubular is displaceable in an axial direction within and with respect to the first tubular wherein, upon displacing the second tubular at a predetermined position within the first tubular: the at least one key element engages with the at least one receptacle and causes the mechanical actuator to actuate the base packing element in the radially inward direction from the retracted position to the extended position; wherein the base packing element bridges a space between the first tubular and the second tubular.

Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

Specific embodiments of the disclosed technology will now be described in detail with reference to the accompanying figures. Like elements in the various figures are denoted by like reference numerals for consistency.

FIG. 1 schematically illustrates, in a cross-sectional elevational view, a packing system for a pair of nested tubulars, in accordance with one or more embodiments.

FIG. 2 schematically illustrates, in accordance with one or more embodiments, the packing system of FIG. 1 , with the second tubular in a second axial position relative to the first tubular.

FIG. 3 schematically illustrates, in accordance with one or more embodiments, the packing system of FIG. 1 , with the second tubular in a third axial position relative to the first tubular, and with a packing element actuated into an extended position.

FIG. 4 schematically illustrates, in accordance with one or more embodiments, in a cross-sectional elevational view, a variant packing system for a pair of nested tubulars.

FIG. 5 schematically illustrates, in accordance with one or more embodiments, the packing system of FIG. 4 , with the second tubular in a second axial position relative to the first tubular.

FIG. 6 schematically illustrates, in accordance with one or more embodiments, the packing system of FIG. 4 , with the second tubular in a third axial position relative to the first tubular, and with packing elements actuated into an extended position.

FIG. 7 schematically illustrates, in an elevational view, a first tubular in a working example of a packing system, in accordance with one or more embodiments.

FIG. 8 schematically illustrates, in an elevational view, the packing system of FIG. 7 with a second tubular, in accordance with one or more embodiments.

FIG. 9 shows a flowchart of a method in accordance with one or more embodiments.

FIG. 10 shows a flowchart of additional method steps in accordance with one or more embodiments.

DETAILED DESCRIPTION

In the following detailed description of embodiments of the disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure. However, it will be apparent to one of ordinary skill in the art that the disclosure may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

Throughout the application, ordinal numbers (e.g., first, second, third, etc.) may be used as an adjective for an element (i.e., any noun in the application). The use of ordinal numbers is not to imply or create any particular ordering of the elements nor to limit any element to being only a single element unless expressly disclosed, such as using the terms “before”, “after”, “single”, and other such terminology. Rather, the use of ordinal numbers is to distinguish between the elements. By way of an example, a first element is distinct from a second element, and the first element may encompass more than one element and succeed (or precede) the second element in an ordering of elements.

Turning now to the figures, to facilitate easier reference when describing FIGS. 1 through 10 , reference numerals may be advanced by a multiple of 100 in indicating a similar or analogous component or element among FIGS. 1-10 .

Generally, in accordance with one or more embodiments, an internally mounted and actuated packer system with multiple internal packers is provided to bridge an annular gap or space between two wellbore tubulars. Particularly, a packer or other sealing arrangement may be mounted on (or otherwise connected with) an inner surface of a “parent” tubular, i.e., a tubular having a larger diameter. The internal packer system may include, or be associated or connected with, a mechanical or hydraulic system which actuates or “sets” the system to bridge the annular gap or space. Mechanical forces applied are transferred down through a string or casing to an activation tool. Hydraulic forces are transferred through a hydraulic median as the fluid column or mechanical hose. Multiple actuation is made possible using selective methods such as keys and profiles, or systematic exposure to hydraulic pressure.

FIG. 1 schematically illustrates, in a cross-sectional elevational view, and in accordance with one or more embodiments, a packing system for a pair of nested tubulars (140, 142). Tubular 140 is generally larger in cross-sectional dimension (i.e., perpendicular to a longitudinal axis, and horizontally in the drawing) and is referred to herein as a “first tubular” or “parent tubular”. Tubular 142 is generally smaller in cross-sectional dimension, can fit and be displaced in an axial direction within (larger) tubular 140, and is also referred to herein as a “second tubular” or “child tubular”. In FIG. 1 , a second tubular 142 is in a first axial position relative to a first tubular 140. As shown, first tubular 140 includes a packing element (or packer) 144 mounted at an inner surface thereof; this may be regarded as a base packing element. The packing element 144 may be embodied by any of a great variety of packers or packing elements known within the oilfield arts. In embodiments disclosed herein, the packing element 144 is annular in shape and is disposed about an entire inner circumference of the first tubular 140. As such, packing element 144 is actuatable between a retracted position and an extended position. When in the retracted position (as shown in FIG. 1 ), packing element 144 may be flush or recessed with respect to the inner surface of the first tubular 140, and (as such) may be disposed in a recess located in the inner surface of the first tubular 140.

As shown, in accordance with one or more embodiments, a first trigger element in the form of one or more receptacles 146 is/are placed at the inner surface of the first tubular 140; two such receptacles 146 are shown here, at different circumferential positions at the inner surface of first tubular 140. In a manner to be better understood herebelow, receptacles 146 may be operatively connected to an actuator 148 which actuates the packing element 144 (e.g., causes it to displace or expand) in a radially inward direction from a retracted position to an extended position. The term “receptacle”, or “receptacles”, as employed herein, may be understood as embodying any of a very wide variety of possible media for interacting with a “key” or “keys” as discussed herein. For example, in one or more embodiments, a receptacle may be embodied by a slot or recess disposed in the inner surface of first tubular 140 (or other analogous tubulars discussed herein). Alternatively, a receptacle may be embodied by a medium that is not necessarily a physical slot or recess but, instead, interacts with a “key” or “keys” in a non-physical manner. By way of non-limiting example, such a “non-physical” receptacle may be embodied by an electronic component that initiates a signal (e.g., to activate the actuator 148) when a compatible “key” (e.g., another electronic component) is adjacent.

In accordance with one or more embodiments, the second tubular 142 is configured to be nested within the first tubular 140 and is displaceable in an axial direction within and with respect to the first tubular 140 (e.g., in a direction shown by the large arrow, up to down in the drawing). Further, a second trigger element in the form of one or more key elements (or keys) 150 is/are placed at an outer surface of the second tubular 142. In FIG. 1 , two such keys 150 are shown, at different circumferential positions at the outer surface of second tubular 142. Those skilled in the art will appreciate that any number of keys 150 and receptacles 146 may be utilized as deemed suitable. For instance, it is possible to employ just one key 150 and one receptacle 146, wherein each may be disposed at a single location about the outer circumference of the second tubular 142 and the inner circumference of the first tubular 140, respectively. On the other hand, a single key 150 may be embodied by an annular protrusion disposed about the entire outer circumference of second tubular 142, and a single receptacle 146 may be embodied by an annular slot or recess disposed throughout the entire inner circumference of the first tubular 140.

In accordance with one or more embodiments, the actuator 148 is a purely mechanical actuator, e.g., a mechanical arm which is tripped when one or more of the keys 150 engage with one or more receptacles 146, and which thereby causes the packing element 144 to displace or expand in the radially inward direction from a retracted position to an extended position. However, other types of actuators are certainly conceivable, e.g., a hydraulic actuator that is powered by hydraulic fluid and actuates a piston or other movable element when one or more keys 150 engage with one or more receptacles 146. The interaction of one or more keys 150 with one or more receptacles 146 is thereby purely mechanical in nature, e.g., to displace an element which itself activates a hydraulic actuator. Alternatively, as mentioned above, keys 150 and receptacles 146 could be embodied by electronic components which interact to activate the actuator 148. In the case of a hydraulic actuator, just by way of an illustrative example, such electronic components could be arranged in suitable manner to detect a pressure difference between regions inside and outside of the first tubular 140, then generate a signal for a hydraulic actuator (148) to actuate the packer 144 at a predetermined threshold pressure (e.g., 1000 psi).

FIG. 2 schematically illustrates the packing system of FIG. 1 , with the second tubular 142 in a second axial position relative to the first tubular 140, in accordance with one or more embodiments. Here, the second tubular 142 has advanced in an axial direction such that keys 150 begin to engage with receptacles 146. In this posture, it should be noted that the keys 150 may be physically compatible with the receptacles 146 in such a way that the keys enter the receptacles once the second tubular 142 has reached a predetermined axial position within the first tubular, whereupon the actuator 148 is caused to actuate.

FIG. 3 schematically illustrates, in accordance with one or more embodiments, the packing system of FIG. 1 , but with the second tubular 142 in a third axial position relative to the first tubular 140, and with the packing element 144 actuated into an extended position. As such, it can be appreciated here that (as conveyed via check marks for illustrative/emphatic purposes) keys 150 are each fully engaged with respective receptacles 146, e.g., have fully entered into receptacles 146 in a way to cause the actuator 148 to actuate the packing element 144 in a radially inward direction from the retracted position to an extended position (and as shown by the horizontal arrows). As shown, in the extended position, the packing element 144 bridges a space between the first tubular 140 and second tubular 142; here, as in one or more other embodiments, the packing element 144 is fully annular in structure and bridges an annular space between the two tubulars 140, 142.

FIG. 4 schematically illustrates, in accordance with one or more embodiments, in a cross-sectional elevational view, a variant packing system for a pair of nested tubulars (540, 542). Tubulars 540, 542 are generally configured similarly to the tubulars 140, 142 illustrated and described with respect to FIG. 1 . Here, a second tubular 542 is in a first axial position relative to a first tubular 540. As shown, first tubular 540 includes two packing elements (or packers) 544, 554 mounted at an inner surface thereof, at different axial positions; these may be regarded as a base packing element and an additional packing element, respectively. Generally, packers 544, 554 are configured similarly to the packer 144 discussed with respect to FIG. 1 . Additionally, a first trigger element in the form of one or more receptacles 546, an actuator 548 which actuates the packing element 544, and a second trigger element in the form of one or more key elements (or keys) 550 are disposed and configured similarly to components 146, 148 and 150, respectively, as described and illustrated with respect to FIG. 1 .

Additionally and as shown, in accordance with one or more embodiments, a third trigger element in the form of one or more receptacles 556 is/are placed at the inner surface of the first tubular 540, at a different axial position with respect to receptacles 546; two such receptacles 556 are shown here, at different circumferential positions at the inner surface of first tubular 540. Receptacles 556 are operatively connected to an actuator 558 which actuates the packing element 554 (e.g., causes it to displace or expand) in a radially inward direction from a retracted position to an extended position; in accordance with a non-restrictive example, operation of the actuator 558 and packing element 554 may be similar to the operation of actuator 548 and packing element 544.

Further, in accordance with one or more embodiments, a fourth trigger element in the form of one or more key elements (or keys) 560 is/are placed at an outer surface of the second tubular 542; two such keys 560 are shown here, at different circumferential positions at the outer surface of second tubular 542. As such, and in a manner to be appreciated herebelow, the receptacles 546 and keys 550 are physically compatible with one another in a manner to trigger the actuator 548, and the receptacles 556 and keys 560 are physically compatible with one another in a manner to trigger the actuator 558. However, as will now be appreciated, there may be different shapes or configurations for the receptacles 546 and keys 548 in comparison with the receptacles 556 and keys 560 (schematically depicted via rectangular and diamond shapes, respectively, in FIG. 4 ) such that each set of keys (550, 560) can only physically engage with one respective set of receptacles (546, 556).

As discussed above with respect to FIGS. 1-3 , and in accordance with one or more variant embodiments, keys 550, 560 and receptacles 546, 556 could be embodied by electronic components which interact to activate the actuators 548 and 558, respectively. In the case of hydraulic actuators, again merely by way of an illustrative example, compatible pairings of such electronic components (550/546 and 560/556) could be arranged in suitable manner to detect a pressure difference between regions inside and outside of the first tubular 540, then generate a signal for a hydraulic actuator (548 or 558) to actuate the respective packer (544 or 554). In this connection, different packers (e.g., 544 and 554) could be actuated at different predetermined threshold pressures. For example, packer 544 may actuate at 1000 psi, packer 554 at 2000 psi, and a (possible) third packer at 2700 psi, etc.

FIG. 5 schematically illustrates, in accordance with one or more embodiments, the packing system of FIG. 4 , but with the second tubular 542 in a second axial position relative to the first tubular 540. Here, the second tubular 542 has advanced in an axial direction such that keys 560 have displaced past receptacles 546. Thus, in displacing past receptacles 546, the keys 560 have not engaged the receptacles 546. To this end, it can be understood that the generally the keys 560 are physically incompatible with the receptacles 546. For example, at least one key 560 may be incompatible with at least one receptacle 546 on the basis of physical shape. In another possibility, at least one key 560 may merely be disposed at a different circumferential position with respect to at least one receptacle 546, such that no physical engagement of the two can even be attempted in the first place. Essentially, this phenomenon can be embodied in any suitable manner, with the common end objective of permitting one or more keys 560 to displace past one or more receptacles 546 such that the keys 560 can proceed to engage (after further axial displacement) with compatible receptacles 556.

As such, in a working example in accordance with one or more embodiments, there may be differences in the number of keys and receptacles for each of the upper and lower “sets” of the same (i.e., 550/546 and 560/556, respectively). For instance, there may be two “upper” keys 550 and two “upper” receptacles 546, while there may also be three “lower” keys 560 and three “lower” receptacles 556. Accordingly, in displacing past receptacles 546, the keys 560 would not engage the receptacles 546 because they would be greater in number than the receptacles 546.

FIG. 6 schematically illustrates, in accordance with one or more embodiments, the packing system of FIG. 4 , but with the second tubular 542 in a third axial position relative to the first tubular 540, and with packing elements 544 and 554 actuated into an extended position. As such, it can be appreciated here that (as conveyed via check marks for illustrative/emphatic purposes) keys 550 and 560 are each fully engaged with respective receptacles 546 and 556, e.g., have fully entered into receptacles 546 and 556 in a way to cause the actuators 548 and 558, respectively, to actuate the packing elements 544 and 554 in a radially inward direction from the retracted position to an extended position (and as shown by the horizontal arrows). As shown, in the extended position, the packing elements 544 and 554 each bridge a space between the first tubular 540 and second tubular 542; here, as in one or more other embodiments, the packing elements 544 and 554 are both fully annular in structure and bridge an annular space between the two tubulars 540, 542.

It should be understood that, while the foregoing discussion with relation to FIGS. 4-6 , in accordance with one or more embodiments, does focus on a system with two packers (544, 554), similar principles and concepts can likewise apply to systems with three or even more packers (e.g., that are each spaced apart from one another along an axial direction with respect to first tubular 540). In such scenarios involving three or more packers, it should also be understood that additional trigger elements (e.g., keys and receptacles) corresponding to each additional packer (above two) can be provided and utilized similarly to the trigger elements described above (e.g., receptacles 546, 556, and keys 550, 560).

FIG. 7 schematically illustrates, in elevational view, a first tubular 840 in a working example of a packing system, in accordance with one or more embodiments. As shown, first tubular 840 includes a packing element (or packer) 844 mounted at an inner surface thereof; this may be regarded as a base packing element. As noted heretofore, packing element 844 is actuable between a retracted position and an extended position. When in the retracted position (as shown in FIG. 7 ), packing element 844 is flush with respect to the inner surface of the first tubular 840, and—to that end—is disposed in an annular recess 862 recess located in the inner surface of the first tubular 840. Also, a first trigger element in the form of one or more receptacles 846 is/are placed at the inner surface of the first tubular 840; two such receptacles 846 are shown here, at different circumferential positions at the inner surface of first tubular 840. As discussed heretofore, receptacles 846 may be operatively connected to an actuator (not shown in FIG. 7 ) which actuates the packing element 844 (e.g., causes it to displace or expand) in a radially inward direction from the retracted position to an extended position. (As such, by way of an illustrative and non-restrictive example, an actuator may be included here which would function similarly to the actuator 148 discussed herein with respect to FIGS. 1-3 .)

FIG. 8 schematically illustrates, in elevational view, the packing system of FIG. 7 but with the addition of a second tubular 842, in accordance with one or more embodiments. As shown, the second tubular 842 is nested within the first tubular 840 and is displaceable in an axial direction within and with respect to the first tubular 840. Further, a second trigger element in the form of one or more key elements (or keys) 850 is/are placed at an outer surface of the second tubular 842; two such keys 850 are shown here, at different circumferential positions at the outer surface of second tubular 842. As such, it can be appreciated here that keys 850 are each fully engaged with respective receptacles 846, e.g., have fully entered into receptacles 846 in a way that causes an actuator to actuate the packing element 844 in a radially inward direction from the retracted position to an extended position. The packing element 844 is shown here in the extended position, and bridges a space between the first tubular 840 and second tubular 842.

FIG. 9 shows a flowchart of a method in accordance with one or more embodiments. Initially, in Step 920, a base packing element is mounted at an inner surface of a first tubular. Further, a first trigger element is placed at the inner surface of the first tubular, the first trigger element being operatively connected with an actuator configured to actuate the base packing element in a radially inward direction from a retracted position to an extended position (Step 922). By way of illustrative example, components for these steps may be embodied by the first (“parent”) tubular 140, actuator 148, packing element 144 and (for the “first trigger element”) receptacles 146 discussed herein with respect to FIGS. 1-3 .

Additionally, in accordance with one or more embodiments, a second trigger element is placed at an outer surface of a second tubular, wherein the second tubular is displaceable in an axial direction within and with respect to the first tubular (Step 924). For its part, by way of illustrative example, the second trigger element may be embodied in the manner of the keys 150 discussed herein with respect to FIGS. 1-3 .

In accordance with one or more embodiments, while displacing the second tubular at a predetermined position within the first tubular (Step 926), a determination is made as to whether the second trigger element is matched to engage with the first trigger element of the first tubular (Step 928). More specifically, a determination is made as to whether the second tubular has reached the correct position within the first tubular such that the second trigger element can engage with the first trigger element. The determination of Step 926 may be made, for example, by the shape of the second trigger element fitting within the shape of the first trigger element. Alternatively, there may be a counter employed that allows the apparatus to know which trigger element to engage with by number. When the second trigger element is matched to the first trigger element (“YES”), the second trigger element engages the first trigger element (Step 930); and the first trigger element causes the actuator to actuate the base packing element in the radially inward direction from the retracted position to the extended position (Step 932). As a result, the base packing element bridges a space between the first tubular and the second tubular (Step 934). By way of illustrative example, these steps (926 through 934) may be carried out in a manner similar to the progression described and illustrated herein with respect to FIGS. 1-3 .

In accordance with one or more embodiments, if the second trigger element is not matched to the first trigger element (“NO”), then the process continues via “A” to FIG. 10 , which illustrates a flowchart of additional method steps in accordance with one or more embodiments. In FIG. 10 , displacement of the second tubular continues with respect to the first tubular (Step 936). That is, the second tubular continues traveling axially within the first tubular, until the correct trigger elements are matched with each other on each tubular.

As shown, in accordance with one or more embodiments, in Step 938, the second tubular is disposed at a further predetermined position within the first tubular. A determination is then made as to whether the second trigger element is matched to engage with an additional trigger element of the first tubular (Step 940). If at this stage the two trigger elements on the two tubular do not match up to engage with each other, then the process returns to Step 936 to continue displacement of the second tubular, and Steps 936-940 are repeated. When the second trigger element is matched to the first trigger element (“YES”), the second trigger element engages the additional trigger element (Step 942). At this point, the additional trigger element can cause an additional actuator to actuate an additional packing element (that, e.g., can mounted at an inner surface of the first tubular) (Step 944). As a result, the additional base packing element bridges the space between the first tubular and the second tubular (Step 946). By way of illustrative example, Steps 938 through 946 may be carried out in a manner similar to the progression described and illustrated herein with respect to FIGS. 4-6 .

It can be appreciated from the foregoing that, broadly contemplated herein, in accordance with one or more embodiments, are systems and methods for using an internal packer to seal a median between two downhole casings. The system thereby replaces externally mounted systems, and obviates their associated disadvantages. Multiple uses of a packer are permitted by way of the embodiments herein, and practical applications may end up obviating a need for components such as liner hangers, liner top packers, stage tools, production packers and temporary inner strings. Generally, a packing system as contemplated herein can be preinstalled in a parent casing (i.e., outer casing), and need only be actuated when an internal casing is run downhole

By way of an additional advantage, in accordance with one or more embodiments, multiple installations can serve as a redundancy, and multiple packers within the same apparatus can also be used for additional redundancies with one actuation. In this connection, it is recognized that packers may occasionally leak or fail, and redundancies offer additional protection. If casing leaks occur in different intervals, then redundancies can isolate leakage to other zones, or to the surface; this prolongs the life of the well, or of the application.

In accordance with one or more embodiments, in yet another advantage, the internally-mounted packer(s) will help accord some flexibility as to where the packer(s) may seal. Particularly, in conventional arrangements where one or more packers are mounted at an external surface of an inner, “child” tubular, they are normally restricted to be actuated where there are corresponding recesses or mating areas at the inner surface of an outer, “parent” tubular. However, in accordance with one or more embodiments as broadly contemplated herein, the packer(s) mounted at the inner surface of the outer, “parent” tubular will be able to actuate essentially anywhere corresponding to the outer surface of the inner, “child” tubular.

In accordance with one or more variant embodiments, wear on packers can be avoided or mitigated via wear resistant options, or via a shiftable protection sleeve (e.g., as embodied by a sheath, coating or sleeve). This will help forestall any structural damage to the packer that might otherwise occur as a second/“child” tubular (e.g., 142 in FIG. 1 ) is displaced downwardly in an axial direction with respect to an outer, first/“parent” tubular (e.g., 140 in FIG. 1 ), such as during run in hole. Further, this can also help provide protection during initial drilling.

As such, by way of a non-restrictive example, a sleeve or sheath could cover one or more packers (e.g., 144 in FIG. 1 ) prior to actuation (i.e., while the packer[s] is/are retracted.). The sleeve or sheath could be shifted (moved axially away from the packer) via any suitable arrangement, e.g., via one or more structural elements on an external surface of the inner, second/“child” tubular (e.g., 142 in FIG. 1 ). The sleeve or sheath can also assist in urging the second tubular radially inwardly to help centralize the same during run in hole. Alternatively, if a sleeve or sheath is not used, one or more wear resistant materials or metallic sealing can be used on the packer(s) to minimize wear; thus, by way of example, such material(s) or sealing can be provided for the packer(s) when in the retracted position.

Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function. 

What is claimed:
 1. A packer system for a wellbore, comprising: a base packing element mounted to an inner surface of a first tubular; an actuator which actuates the base packing element in a radially inward direction from a retracted position to an extended position; a first trigger element disposed at the inner surface of the first tubular, wherein the first trigger element is operatively connected with the actuator; and a second trigger element disposed at an outer surface of a second tubular; the second tubular being displaceable in an axial direction within and with respect to the first tubular; wherein, upon displacing the second tubular at a predetermined position within the first tubular: the second trigger element engages with the first trigger element; and the first trigger element causes the actuator to actuate the base packing element in the radially inward direction from the retracted position to the extended position, wherein the base packing element bridges a space between the first tubular and the second tubular.
 2. The packer system according to claim 1, wherein the actuator comprises a mechanical actuator.
 3. The packer system according to claim 1, wherein the actuator comprises a hydraulic actuator.
 4. The packer system according to claim 1, wherein the base packing element, when in the retracted position, is disposed to be flush or recessed with respect to the inner surface of the first tubular.
 5. The packer system according to claim 1, wherein the base packing element, when in the retracted position, is disposed in a recess in the inner surface of the first tubular.
 6. The packer system according to claim 1, wherein: the first trigger element comprises at least one receptacle; and the second trigger element comprises at least one key element which engages with the at least one receptacle to cause the actuator to actuate the base packing element in the radially inward direction from the retracted position to the extended position.
 7. The packer system according to claim 6, wherein the at least one key element comprises at least one structural element which is physically compatible with the at least one receptacle.
 8. The packer system according to claim 1, further comprising: a second packing element mounted to the inner surface of the first tubular, at a different axial position than the base packing element; a second actuator which actuates the second packing element in a radially inward direction from a retracted position to an extended position; a third trigger element disposed at the inner surface of the first tubular, wherein the third trigger element is operatively connected with the second actuator; and a fourth trigger element disposed at an outer surface of the second tubular; wherein, upon displacing the second tubular at a predetermined position within the first tubular: the fourth trigger element engages the third trigger element; and the third trigger element causes the second actuator to actuate the second packing element in the radially inward direction from the retracted position to the extended position, wherein the second packing element bridges a space between the first tubular and the second tubular.
 9. The packer system according to claim 8, wherein the fourth trigger element does not engage the first trigger element when moving axially past the first trigger element.
 10. The packer system according to claim 9, wherein: the third trigger element comprises at least one receptacle; and the fourth trigger element comprises at least one key element which engages with the at least one receptacle of the third trigger element to cause the second actuator to actuate the second packing element in the radially inward direction from the retracted position to the extended position.
 11. The packer system according to claim 10, wherein the at least one key element of the fourth trigger element comprises at least one structural element which is physically compatible with the at least one receptacle of the third trigger element.
 12. The packer system according to claim 11, wherein the first trigger element comprises at least one receptacle which is physically incompatible with the at least one key element of the fourth trigger element.
 13. A method comprising: mounting a base packing element at an inner surface of a first tubular; disposing a first trigger element at the inner surface of the first tubular, the first trigger element being operatively connected with an actuator configured to actuate the base packing element in a radially inward direction from a retracted position to an extended position; disposing a second trigger element at an outer surface of a second tubular, the second tubular being displaceable in an axial direction within and with respect to the first tubular; while displacing the second tubular at a predetermined position within the first tubular, determining whether the second trigger element is matched to engage with the first trigger element of the first tubular; and when the second trigger element is matched to the first trigger element: the second trigger element engages the first trigger element; and the first trigger element causes the actuator to actuate the base packing element in the radially inward direction from the retracted position to the extended position, wherein the base packing element bridges a space between the first tubular and the second tubular.
 14. The method according to claim 13 wherein the base packing element, when in the retracted position, is disposed to be flush or recessed with respect to the inner surface of the first tubular.
 15. The method according to claim 13, wherein: the first trigger element comprises at least one receptacle; and the second trigger element comprises at least one key element which engages with the at least one receptacle to cause the actuator to actuate the base packing element in the radially inward direction from the retracted position to the extended position.
 16. The method according to claim 13, further comprising: mounting an additional packing element at the inner surface of the first tubular, at a different axial position from the base packing element; disposing a third trigger element at the inner surface of the first tubular, the third trigger element being operatively connected with an additional actuator which actuates the additional packing element in a radially inward direction from a retracted position to an extended position; disposing a fourth trigger element at an outer surface of the second tubular; while displacing the second tubular at an additional predetermined position within the first tubular, determining whether the fourth trigger element is matched to engage with the third trigger element of the first tubular; and when the fourth trigger element is matched to the third trigger element: the fourth trigger element engages the third trigger element; and the third trigger element causes the additional actuator to actuate the additional packing element in the radially inward direction from the retracted position to the extended position; wherein the additional packing element bridges the space between the first tubular and the second tubular.
 17. The method according to claim 16, wherein the fourth trigger element does not engage the first trigger element when displaced past the first trigger element.
 18. The method according to claim 17, wherein: the third trigger element comprises at least one receptacle; and the fourth trigger element comprises at least one key element which engages with the at least one receptacle of the third trigger element to cause the additional actuator to actuate the additional packing element in the radially inward direction from the retracted position to the extended position.
 19. The method according to claim 18, wherein: the at least one key element of the fourth trigger element comprises at least one structural element which is physically compatible with the at least one receptacle of the third trigger element; and the first trigger element comprises at least one receptacle which is physically incompatible with the at least one key element of the fourth trigger element.
 20. A packer system for a wellbore, comprising: a base packing element mounted at an inner surface of a first tubular and which, when in a retracted position, is disposed to be flush or recessed with respect to the inner surface of the first tubular; a mechanical actuator which actuates the base packing element in a radially inward direction from a retracted position to an extended position; at least one receptacle which is placed at the inner surface of the first tubular and is operatively connected with the mechanical actuator; and at least one key element placed at an outer surface of a second tubular and which is physically compatible with the at least one receptacle; the second tubular being displaceable in an axial direction within and with respect to the first tubular; wherein, upon displacing the second tubular at a predetermined position within the first tubular: the at least one key element engages with the at least one receptacle and causes the mechanical actuator to actuate the base packing element in the radially inward direction from the retracted position to the extended position; wherein the base packing element bridges a space between the first tubular and the second tubular. 